Connecting Old Devices to New Macs

Where is the audio input jack on my new Mac? [9 & X]

Many
recent Macs lack analog audio input jacks, but they made a comeback
on some Macs introduced in 2002. If you need to feed analog audio
into a Mac that lacks an analog input, you need a USB audio
interface, like a Griffin iMic (which is not a microphone at all, but
rather a line/mic level to USB adapter), or a more advanced interface
like an Edirol UA-1A or Roland UA-3D. If you are serious about audio
on the Mac, you will be looking at more sophisticated products, such
as the Digidesign mBox or 001, or a FireWire audio interface, such as
the Metric Halo products or DigiDesign 002.